Women with early-stage breast cancer have a few options when it comes to how to treat the disease. That choice can be based on the particularities of the cancer, to personal preference or, as is often the case, the recommendations of health groups, breast surgeons and oncologists. Certain data that would be helpful in informing that choice can be scant, however, including long-term health outcomes to the costs of different treatments. Now, two new studies add more nuance to the picture.

The first study, presented Thursday at the 2015 San Antonio Breast Cancer Symposium, found that mastectomies followed by breast reconstruction was both costlier and came with more complications than lumpectomies (sometimes referred to as breast-conserving therapy) followed by radiation.

In the study, Dr. Benjamin D. Smith, an associate professor and research director of the breast radiation oncology at the University of Texas MD Anderson Cancer Center, and his team used two databases to look up insurance claim information on younger and older women who were diagnosed with early-stage breast cancer in 2000 through 2011. The researchers also looked at results from the different treatment options offered to women with early-stage breast cancer. The studied authors assessed complications from the women’s treatments as well as complication-related costs and total costs.

They found the risk for complications from mastectomy with reconstruction but without radiation was double that of lumpectomy with radiation for older and younger women. Costs from complications for the mastectomy with reconstruction was $8,608 higher compared to lumpectomy with radiation for younger women with private insurance and $2,568 higher for older women on Medicare.

One of the reasons some women opt for lumpectomy over mastectomy is that the procedure preserves the breast as much as possible. Many women who choose the mastectomy option, on the other hand, stress that it allows them to avoid radiation. (Others say they prefer surgery because they think it means they can’t have a recurrence of the cancer, which is incorrect.)

The rates of mastectomy and reconstruction rates have been on the rise in the U.S. over the last 10 years, and his study helps parse the harms associated with the procedure compared to others. “I was very surprised. I wasn’t expecting there to be such a difference, especially in terms of cost,” says Smith.

A second study led by Sabine Siesling, a senior researcher at the Netherlands Comprehensive Cancer Organisation, similarly found that breast-conserving therapy resulted in better health outcomes compared to mastectomies for women with early-stage breast cancer. Siesling and her team looked at the overall survival and disease-free survival rates among women after breast-conserving therapy or mastectomy.

They studied two groups of thousands of women with early-stage breast cancer and found that the women who underwent breast-conserving therapy were 21% more likely to still be living 10 years later compared to the women who underwent mastectomy. When looking at the smaller of the two cohorts, they also found that the women who underwent brachytherapy—an advanced procedure that that involves placing radioactive material inside your body—developed fewer regional recurrences or distant metastases (cancer that spreads from the initial organ to elsewhere in the body) compared to women who had mastectomies.

“I think this will be surprising for women because most trials and observational studies said there were similar prognosis. I think some women feel more secure if they’ve had they’ve had their breast amputated,” says Siesling. “I think the main message is that women should be very well informed at the time of decision-making.”

Dr. Mehra Golshan, a surgical oncologist at the Dana-Farber/Brigham and Women’s Cancer Center says the findings underline the basic fact that when you do a bigger surgery, there’s a longer recovery time which could contribute to more complications. “Women and and providers should know that once you do the surgery the woman should be prepared to deal with the wounds and recovery and possibility other surgeries,” he says. Golshan was not involved in the study.

Dr. Shelley Hwang, a surgical oncologist at Duke Medicine, says the findings have limitations since the women in the study get to choose what group they are in (since they choose their treatment method). There are other factors that women may take into account, like family history, that can’t be accounted for in the research design. Women who get more treatment might have a different risk, she says. “Overall, this underscores the findings of prospective randomized trials which show that breast-conserving therapy is not worse [than mastectomy], but the magnitude of benefit of breast-conserving therapy is difficult to quantify since there are imbalances in the groups,” she says. Hwang was also not involved in the trial.